Process for the production of diesters of hydroxy carboxylic acids



inteiute June 3% PROCESS FOR THE PBODWCTION OF DI- Egg'g-RS F HYDROXY CQXYMIC A 8 Edward M. Filochione, Philadelphia, and Charles H. Fisher, Ablngton, Pa., asslgnors to the United Stnteo of America, as represented by the Secreiery of Agriculture No Drawing. Application October 16, 1943, Serial No. 506,528

4 Claims. (c1. 260-484) (Granted under the act of Moi-ch 3,1883, as

amended April 30, 1928; 3'10 0. G. 757) l 2 This application is made under the act of can be obtained at low cost by acetylatin lactic March 3, 1883, as amended by the act of April acid with acetic acid in the presence of an acid 30, 1928, and the invention herein described and catalyst and a. suitable entraining agent, such as claimed, if patented, may be manufactured and benzene, ethylene chloride, or toluene. The byused by or for the Government of the United products formed in our process can be used in States of America for governmental purposes succeeding preparations.

without the payment to us of any royalty thereon. The following examples illustrate our inven- This invention relates to the production of dition: esters of hydroxy carboxylic acids, such as alkyl Example I alpha'acetoxypmpiom'tes' The term I'm-ester m A mixture of 66 g. (0.5 mole) of elpha-acetoxyas used herein is defined as an ester of an hypropionic acid, 92.5 g. (1.25 moles) of methyl dmxy acid resulting when both the carboxyl group acetate, and 0.5 ml. of concentrated sulfuric acid and the hydroxyl group are estel'medwas heated in a closed bottle ("Mcgnesia bot- Iusknown that dl'esters of hydmxy camxync tie) at 100 C. for 4' hours. The catalyst was 3:13; is g giy gi g m g fi g g a g gggg then neutralized with 2.0 g. of sodium acetate, Jones and Ritchie, J. Chem. Soc. 1935, and the methyl alpha emypmpmmte and 400; 1941; smith and by distillation. There resulted a conversion of workers Chem 473 (1942) ketene 33 percent into methyl elphe-acetoxypropionate. (whom and smith Chem 2727 The yield calculated on the basis of alpha-seed (1939)),and acetyl chloride (Purdie and Williamoxypmpiomc acid consumed was 61 percent son, J. Chem. Soc. 69, 828). Furthermore, it is y known that alpha-ncetoxypropionyl chloride Example H FEMS alkyl alpha-'wemxypmplonates when treat- An experiment identical with that in Example ed with alcohols (Freudenbel'g and Mame, I except that a. higher molar ratio of methyl oce- 2447 (1927) A disadvantage these tats to alphn-acetoxypropionic acid was used (5 methods is that relatively inaccessible and expento 1 instead of 2.5 to 1, as in Example I) gave a. sive acid cnhydrides or acid chlorides are used 33 percent conversion into methyl alpha-acetgxy. mtelmedia-ws- Accordingly an object this propionate; the yield based on unrecovered acetinvention is to provide a. simple, efficlent and lowoxypmpiomc acid was 77 percent cost process for manufacturing ail-esters of hy- E l I drony cnrhoxylic colds. 6

A f rth r j ct is to prov de a suitable m Two and one-half moles of methyl acetate and d f r pr ing methyl alph -w wxypl' p 0.5 ml. or concentrated sulfuric acid were added note. which decomposes t m t c y te a d to 0.5 mole of alpha-acetoxypropionic acid. After acetic cold when pyrolyzed. heating for 4 hours in a glass lined bomb at 120 A f rth r O ject is to provide a Satisfactory to 126 0., the mixture was neutralized with somcthcd f0 wnvertim; fi p -fl p p dium acetate and distilled. There resulted a. 54 acid, which is readily obtainable from lactic acid, percent conversion, and an 81 percent yield of infinite a yl esters. methyl aipha-acetoxypropicncte. Other objects will appear from the following de- Example IV scription.

We have found that in the presence of acid This experiment was carried out as in Example cctclysts, such he sulfuric acid, phosphoric acid, 111 except that a. higher temperature of reaction hydrogen chloride and tolueneculfonic cold. ccylwas used, 1. e., 140 to 160 C. The result was a. city ccrboxylic acids react reudily with ccrbox- 60 percent conversion and an to percent yield ylic cold esters to form the corresponding dl-esof methyl alphe-acetoxypropionate.

ter. Thus, we have found thnt alphe-acetoxy- Exampze V propionic cold reacts with alkyl acetates to form clhyl ccetoxypropionates. The preparation of A mixture of 0.5 mole oi alphs-acetoxypropinlityl cipho-ccetoxypropionates by our process onic acid, 2.5 moles of ethyl acetate and 0.5 ml. oi avoids entirely the use of acetic anhydride, ncctyl concentrated sulfuric acid was heated in a. glass chloride, end or reagents which have been lined bomb for 4 hours at 122 to 130 C. The required by previous methods. The alphafl-cceh catalyst was neutralized with sodium acetate and w? ionic cold rrcd for these syntheses the mixture distilled. There resulted 9.52 percent reacted alphn-acetoxypropionic acid were isolated conversion and a 64 percent yield oi ethyl aipha-' acetoxypropionate.

Example VI A mixture of 0.5 mole of alpha-acetoxypropionic acid, 0.7 mole phenyi acetate and 0.5 ml. of concentrated sulfuric acid was heated for hours in apparatus containing a Vigreux column. The bath temperature was 125 to 140 C., and the system was maintained at a pressure of mm. in order to distill the acetic acid as formed. However, the amount of acetic acid which distilled during the reaction was slight. After neutralization of the sulfuric acid with sodium acetate. the mixture was distilled. The phenyi alphaacetoxypropionate and unreacted aipha-acetoxypropionic acid, which boil ver close together, were collected at 112 to C. under 1 to 2 mm. of mercury pressure. This fraction was then washed with sodium bicarbonate solution to give pure phenyl alpha-acetoxypropionate; B. P. 103 to 104 C. at about 1 mm. The conversion was 20 percent and the yield, based on unrecovered alpha-acetoxypropionic acid, was 45 percent. Index of refraction (n at 20 C.) was 1.4835.

Example w! A mixture of 0.5 mole of aipha-acetoxypropionic acid, 1.0 mole of benzyi acetate and 0.5 mi. of concentrated sulfuric acid was heated in dis- 0 tillation equipment for 4 hours at to C. under 50 mm. of pressure. After neutralization of the catalyst, the mixture was dietiiied. A con version of 34 percent and a, 61 percent yield of benzyl alpha-acetoxypropionate resulted,

Having thus described our invention, we claim:

1. The process which comprises reacting alphaacetoxypropionic acid with a compound selected from the group consisting oi alixyi and and see. tates, in the presence of an acid catalyst at a temperature of the order oi 100 to 0.. to form the corresponding alkyl or aryi alpha-acetoxypropionate.

2. The process which comprises reacting alpha.- acetoxypropionic acid with methyl acetate, in the presence of a. catalytic amount of sulfuric acid at a temperature of the. order of 100 to 150 0., to form methyl alpha-acetoxypropionate.

3. The process which comprises reacting alphaacetoxypropionic acid with phenyl acetate,in the presence of a catalytic amount of sulfuric acid at a temperature of the order of 100 to 150 0., to form phenyl alpha-acetoxypropionate,

4. The process which comprises reacting alphaacetoxypropionic acid with benzyl acetate, in the presence of a catalytic amount of sulfuric acid at a. temperature of the order of 100 to 150 0.. to form benzyl alpha-acetoxypropionete.

EDWARD M. CHIONE. CHARLES H. FIB. 

